Effects of Barrier-Metal Schemes of Tungsten Plugs and Blanket Film Deposition

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Abstract
This work investigates the effects of various contact integration schemes on tungsten (W) plug formation. The deposition rate, surface morphology, sheet resistance and reflectivity of W deposited on various substrates are also characterized. Experimental results indicate that the titanium nitride (TiN) film which does not undergo post-rapid-thermal-processing (RTP) treatment has a higher W deposition rate than TiN film which under goes the post-RTP treatment. The W plug formed on chemical vapor deposition (CVD) TiN has easily found voids, which result in high contact resistance. To reveal the relationship of CVD TiN process conditions and W plug loss, process variables including film thickness, plasma ambient, in situ plasma treatment periods and cycles are tested. According to these results, plasma ambient has a strong influence on W plug loss during the etch-back process. In addition, the electrical characteristics of various contact integration schemes are examined in terms of both n+ and p+ contact resistance. This work also proposes a superior contact integration scheme to achieve low contact resistance and high production efficiency.

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